Montenegro says "Russian state bodies" were involved in a thwarted assassination plot to kill the Balkan nation's prime minister and derail its accession to Nato.

The special prosecutor investigating the election day plot made his first public accusation of state involvement a day after it was reported that the British government believes Russia backed the conspiracy.

The Kremlin immediately dismissed the allegations it conspired to use Serbian nationalists to overthrow the Montenegrin government as "absurd" and unsubstantiated.

Milivoje Katnic, prosecutor, told local television: "So far we have had evidence that Russian nationalist structures were behind [the plot], but now also that Russian state bodies were involved at a certain level.

"The organs of the Russian state must investigate which bodies are involved and open a criminal trial over these acts."

The prosecutor alleged the conspiracy, which would have seen a group disguised as police officers attack parliament on October 16 and kill Milo Djukanovic, had been approved by a member of Russian military intelligence. British and US intelligence agencies have been called in to help the Montenegrin authorities unravel the plot and are understood to have found evidence of Russian involvement. Mr Katnic said one of the local ringleaders, a Serb activist called Aleksandar Sindjelic who has since turned prosecution witness, was invited to Moscow by a man called Eduard Sismakov, a member of "Russian military structures", to be cleared for the mission. He said Mr Sismakov, using the alias Shirokov, "asked him to work first to prevent Montenegro from entering Nato. That is the sole motivation of these structures".

Interpol has already issued a wanted notice for 'Eduard Shirokov' and another Russian called Vladimir Popov. Montenegro alleges they are officers with the GRU military intelligence service and oversaw the plot planning.

Mr Sismakov was deputy Russian military attaché in Poland before being expelled for espionage in 2014, Mr Katnic said. In 2014 there were several tit-for-tat expulsions involving Russia and Poland, but the people expelled were never publicly named.

Moscow denied the claims as absurd and irresponsible.

Dmitry Peskov, Vladimir Putin's spokesman, said: "There can't be even talk about any sort of Russian officials' interference into Montenegro's internal affairs. Russia hasn't interfered and isn't going to interfere into domestic affairs of other countries, and in particular Montenegro with which we have very good relations."